(5) Metastatic Breast Cancer
How will my oncologist decide how to treat my metastatic breast cancer?
Treatment of metastatic breast cancer can prolong life and enhance its quality, but there is no cure. Therefore, your oncologist’s strategy is to get as much mileage out of each treatment regimen as possible.
Since treatments with the fewest side effects are preferred, your oncologist will try to use hormonal therapies instead of chemotherapy, whenever reasonable. Of course, hormonal therapy is only an option if your breast cancer is estrogen or progesterone receptor positive.
Many women with hormone receptor positive breast cancer benefit from sequential hormone therapies when their disease progresses. Premenopausal women who have had anti-estrogen adjuvant therapy (usually tamoxifen) will typically be treated with an aromatase inhibitor (like anastrozole) after they are put into a postmenopausal state by an oophorectomy (surgically, or induced with radiation therapy or with medicines such as goserelin or luprolide).
Tamoxifen is an option for first-line hormonal therapy if you are premenopausal and have never received anti-strogens, or it has been more than 1 year since you stopped taking them. An aromatase inhibitor (anastrozole, letrozole, exemestane) is the first-line hormonal therapy if you are postmenopausal. The antiestrogen fulvestrant (Faslodex) recently became available for the treatment of postmenopausal women with hormone receptor-positive metastatic breast cancer that has been previously treated with an anti-estrogen. It has the advantage of being administered as a once a month intramuscular injection. Other hormone therapies include progestin (megestrol acetate), androgens (fluoxymesterone), and high-dose estrogens (ethinyl estradiol).
Hormone therapy is especially useful in patients whose metastatic disease involves only bone or soft tissue. Though it is also useful in treating metastases to the vital organs (especially if there are no symptoms), chemotherapy will be recommended in these situations. Even if your metastases remain limited to the bone or soft tissue, once your cancer stops responding to hormonal therapy, your oncologist will have no other choice but to switch to chemotherapy. Of course, if your cancer is not estrogen receptor positive or progesterone receptor positive, chemotherapy is your only option.
If your breast cancer has an HER2 overexpression of the oncogene, your oncologist will probably recommend targeted therapy with trastuzumab (Herceptin), or, if you have already received trastuzumab (Herceptin), the newer agent, lapatinib (Tykerb). He can give trastuzumab to you as a single agent, but often will combine it with traditional cytotoxic chemotherapeutic agents like paclitaxel (Taxol). Trastuzumab can have debilitating heart toxicity, and your oncologist will need to make sure that you are not at risk before he administers this drug to you.
Even if your tumor is HER2 positive, if you meet the criteria for hormonal therapy, most oncologists prefer to go that route before resorting to trastuzumab. If your breast cancer is HER2 negative, your oncologist may still choose a targeted therapy for you. Bevacizumab (Avastin) is an active first-line therapy for women with metastatic breast cancer. Your oncologist can give this to you as a single agent, but a study has shown that it is more effective when given in combination with paclitaxel.
Patients with uncontrolled hypertension, recent surgery, or brain metastases are at increased risk for bevacizumab-related bleeding or a rip (perforation) in the intestines. Your oncologist will need to be sure that you do not have these conditions, or other risk factors, before he administers the drug.
Metastatic breast cancer is sensitive to many cytotoxic chemotherapy agents. The following are among those most commonly used as first-, second-, or subsequent line treatment. You could get these as single agents or in various combinations: paclitaxel, docetaxel, capecitabine, gemcitabine, vinorelbine, doxorubicin, epirubicin, pegylated liposomal doxorubicin, cyclophosphamide, fluorouracil, cisplatin, and carboplatin.
Patients often ask what the “best” treatment regimen is. Oncologists will differ on how they answer that question. What they will all tell you is that there really is no good way of knowing without first trying. The order in which they choose to use these palliative agents will depend upon your overall health, the location of your metastases, and your track record with previous treatment regimens. After a certain point, the choice is more “art” and personal preference than “science.”
The order in which they choose to use these palliative agents will depend upon your overall health, the distribution of your metastases, and your track record with previous treatment regimens.
Adjuvant therapy - Treatment given after the primary treatment to increase the chances of a cure.
Radiation therapy - The use of high-energy X-rays to kill cancer cells and shrink tumors.
First-line therapy - The first drug or set of drugs that you receive as your treatment.
Cytotoxic - A term used to describe anything that kills cells.